Lift vehicles, such as helicopters, are used to move payloads through the air more rapidly than using ground transportation and/or to locations that are unreachable via ground transportation. In situations in which the payload weighs more than a single lift vehicle can carry, multiple lift vehicles may be used to cooperatively carry the payload. However, such maneuvers are dangerous due to the risk of collision between lift vehicles operating in relatively close proximity.
Unmanned lift vehicles, which are controlled by an external control system that coordinates the movements of the lift vehicles, have been developed to perform cooperative lifting. Known unmanned lift vehicles rely on centralized control utilizing information from each vehicle and generation of coordinated commands for each vehicle. Thus, known unmanned lift vehicles are highly sensitive to losses in communication capability and, as a result, have limited ranges and applications. Furthermore, such unmanned lift vehicles are highly sensitive to the loss of one or more of the cooperating lift vehicles, even if there is sufficient payload carrying capability in the remaining cooperating lift vehicles, due to the inability to rapidly adjust the control scheme to account for the change in the loads on the individual vehicles. It is therefore advantageous to provide a control system for cooperative lift vehicles that is robust against and/or independent of a lack of external communication. It is also advantageous to provide a control system for cooperative lift vehicles that is robust against losses of lift vehicles during a cooperative lift.